Repair of potentially lethal damage (PLD) and the effect of hyperthermia on repair of PLD in normal and malignant C3H-10T1/2 cells

Transformation was induced in the C3H 10T1/2 mouse embryo cell line by ionizing radiation or transfection with the H-ras oncogene. After 4-8 weeks, cell clones with a transformed morphology developed and cell colonies with a transformed morphology were isolated and grown up to larger populations. Cells from these populations were cloned in microwells and resulting colonies with transformed morphology were isolated for further testing. These cell lines produced tumours in nude mice while the normal parental cell line did not. These cell lines showed small differences in their radiosensitivities while larger differences were found in their heat sensitivities. Repair of potentially lethal radiation damage (PLD) was greater in some of the transformed cell lines than in the parental cell line also PLD repair was greater at the acid pH than at pH 7.4. Hyperthermia and Ara A both inhibited the repair of PLD in both normal and transformed cells